Austropuccinia psidii is a pathogenic fungus that causes rust in the Myrtaceae plant. The extensive plantation of the host of this fungus has increased the attack of fungal pathogen, therefore, will increase the threat tothe presence of Myrtaceae species around the globe including in Indonesia. This present study was aiming to detect and identify the presence of this pathogen by morphologicaland molecular observation. Morphological observationrevealed the presence of A. psidii urediniospores onsalam (Syzygium polyanthum) andkayuputih (Melaleuca cajuputi)leaves collected from the arboretum of the Indonesian Center for Forest Biotechnology and Tree Improvement (CFBTI), and the presence of teliospores on young Syzygium leaves. PCR amplification using specific primers of Ppsi1 / Ppsi6 succeeded in detecting the presence of A. psidii fungi Melaleuca and Syzygium showed by DNA amplicon length around 500bp. Efforts to obtain ITS DNA sequences to compare the molecular characteristics of fungi from two different hosts have been carried out, however, the sequencing electropherogram was unreadable, so the comparison can not be performed. This study reported that A. psidii is currently present in Myrtaceae species in Yogyakarta, therefore precaution efforts should be conducted to avoid economic and ecological impact from this pathogen.

Austropuccinia psidii is an invasive pathogenic rust that infects the Myrtaceae family. This rust is a threat to Myrtaceae plantations around the world due to its widespread distribution. In this study, we observed the presence of A. psidii in three species of Myrtaceae, i.e. Melaleuca cajuputi, Syzygium myrtifolium, and Syzygium polyanthum planted in Yogyakarta and Sukabumi. The symptoms of infection were yellow-reddish spot in young leaves, presence of urediniospores in infected spot, foliage, and branch dieback. To confirm the presence of A. psidii on those trees, a molecular detection was performed using specific primer for A. psidii (Ppsi1/Ppsi6) on DNA samples extracted from diseased leaves. The presence of A. psidii was proved by the presence of DNA amplicon sized around 500bp in all samples collected from three different hosts. In this study, S. myrtifolium was firstly reported to be infected by this rust in Indonesia. Further study about the presence and the economic impact of this pathogen in Indonesia should be conducted. Indonesia has many species numbers of Myrtaceae and some species are important for medicines, herbs, foods, and as industrial plants. A strategy to control this pathogen should be established to avoid large economic losses in Myrtaceae plantations in Indonesia.

In vivo control activities test of BCA candidate is required to evaluate its effectiveness. This test involved identification of the fungal species that inhabited the experimental plant after inoculation of BCA and pathogen. Identification of inhabitant fungi in the BCA control activity test can be conducted by culturing the fungi on artificial media. Fungal species can be identified based on morphological characters or genetic characters of fungal culture. This study was conducted to determine the potential of PCR ITS -RFLP molecular markers in the initial selection process of fungal isolates before identification based on DNA sequences and to select the enzyme that produce polymorphic PCR ITS RFLP pattern. Three enzymes (DraI, EcoRI and HinfI) were successfully separated 8 fungal cultures used in this study into three groups based on the pattern of PCR ITS DNA, while five other enzymes (BamHI, BclI HaeII, HpaI, and HindIII) were failed to cut the DNA ITS fragments, except for one isolate.

Abstract. Faradilla FA, Prihatini I, Suranto, Susilowati A. 2022. Genetic variation of Austropuccinia psidii in some species of Myrtaceae as host plants in Java, Indonesia based on simple sequence repeats (SSR) markers. Biodiversitas 23: 256-263. Austropuccinia psidii is pathogenic rust with a wide host and is considered a biosecurity threat to the Myrtaceae family in many countries. The genetic variation of this rust in Java, Indonesia is poorly reported. Therefore, this study aimed to determine the genetic variation among A. psidii from different Myrtaceae hosts, namely Syzygium polyanthum, S. myrtifolium, and Melaleuca cajuputi from three different locations in Java using seven simple sequence repeats (SSR) markers. Data were collected from 28 A. psidiisamples from three different hosts and locations in Java. The genetic variations of A. psidii were found in six isolates in locus USYD_Pp168, PpSSR161, and PpSSR195*. The results showed that the expected heterozygosity value among 12 isolates of A. psidii is 0.312. The dendrogram illustrates two clusters constructed with cluster I consisting of subcluster IA (S1, S3, S4, S5, K1, K2, K3, K4, and P1) and IB (P2); and cluster II consists of isolates S2 and S6. Principal Coordinate Analysis (PCoA) was used to demonstrate the similarity and dissimilarity among isolates based on microsatellite sites. Axis 1 and 2 explained 87.7 % of the total variations and sep a rated isolate S1, S2, S3, S4, S6 from other isolates, and grouping the rest of isolates together. The dendrogram and PCo analysis demonstrated A. psidii isolates tend to have close genetic similarity based on their host.